1. Field of the Invention
The present invention relates to methods of interleaving bits for coding, transmission, or storage, and more specifically to implementations of the bit re-ordering table for full-rate speech, Table 1 in GSM 05.03.
2. Description of Related Art
A method for encoding full rate speech is specified in the Global System for Mobile Communications' technical specification 05.03 (GSM 05.03) "Digital cellular telecommunications system (Phase 2+); Channel coding" version 5.1.0, May 1996. This publication is hereby incorporated by reference as though completely set forth herein.
The encoding method includes an interleaving process which is carried out in order to combat the burst errors that occur due to the mobile channel. Interleaving helps to separate out the individual errors within any error bursts and thereby effectively randomize the bit errors that are present. Then it is the job of a random error correcting code such as a convolutional code to correct as many of the errors as possible. The interleaver operates to reorder and spread bits from forward error correction (FEC) coded frames into data blocks for time division multiple access (TDMA) data bursts.
Prior art interleaving is performed by taking a single, current speech frame and distributing the bits throughout eight data blocks. Consequently, this prior art method requires that eight data blocks be simultaneously maintained in memory while speech frame bits are distributed among them.